1. Field of the Invention
The present invention relates to a process cartridge detachably attached to an image forming apparatus, and more particularly to a process cartridge configured to accommodate an image carrier and at least one image forming process device.
2. Discussion of the Related Art
In an image forming apparatus such as a copying machine, a printer, a facsimile machine, or other similar devices, an electrostatic latent image formed on a photoreceptor functioning as an image carrier is developed with toner by a developing device to obtain a visual image, i.e., a toner image. Next, the toner image is transferred onto a recording medium such as a sheet in a transfer process.
With regard to the transfer process, in the case of single color image formation, a toner image may be directly transferred from a photoreceptor to a sheet. In the case of multi-color image formation, toner images of different colors formed on respective photoreceptors may be sequentially transferred onto a sheet while being superimposed upon each other on the sheet. Alternatively, toner images of different colors formed on respective photoreceptors may be sequentially transferred onto an intermediate transfer element, i.e., a primary transfer, while being superimposed upon each other on the intermediate transfer element. Also, the multi-color image superimposed on the intermediate transfer element may be collectively transferred onto a sheet during a secondary transfer.
An image forming apparatus, in which a plurality of image forming devices, including photoreceptors, are arranged along an intermediate transfer element in the direction of movement of the intermediate transfer element, is called a tandem-type image forming apparatus. A tandem-type image forming apparatus is described in, for example, Published Japanese patent application No. 2002-14596:
As described in Published Japanese patent application No. 2002-14596, devices used for image formation, such as, a photoreceptor, a charging device, etc. (hereafter referred to as “image forming process devices”), are configured to be pulled out from an inserted position to a pulled-out position in the main body of an image forming apparatus for repair, maintenance check, or replacement with new ones at the end of their useful life.
Published Japanese patent application No. 2002-297002 describes a process cartridge which integrally accommodates image forming process devices. However, when the process cartridge is pulled out from and inserted into the main body of such a device for repair, maintenance check, or replacement, care must be exercised in order to avoid damaging the image forming process devices, especially, a photoreceptor, for example, by touch. Therefore, touching of the photoreceptor is prevented by covering it with a covering member, such as, a shutter. In addition, when removing the process cartridge from the main body of the image forming apparatus, the process cartridge is pulled out in the axial direction of the photoreceptor.
Published Japanese patent application No. 2002-196647 describes a process cartridge which is taken out from the main body of an image forming apparatus in a direction perpendicular to an axial direction of a photoreceptor. In these devices, if a process cartridge is inserted or removed from the image forming apparatus by moving it upward and downward, a space for removing the process cartridge is required. That is, sufficient space needs to be provided above an upper portion of the image forming apparatus. Recently, demands for reducing the size of image forming apparatuses continue to increase. In the case of a relatively small image forming apparatus, space may be easily provided at a region around an upper portion thereof. However, in the case of a relatively large image forming apparatus of the type generally used in an office and capable of producing a large number of prints or copies, it may be difficult to provide sufficient space anywhere in the image forming apparatus.
Therefore, it is desirable to provide a process cartridge that can be easily inserted and removed from the main body of an image forming apparatus without damaging any of the image forming process devices assembled in the process cartridge and without, at the same time, increasing the cost of the process cartridge. Further, it is desirable to provide an image forming apparatus with enhanced operability to insert and remove such a process cartridge from its main body.